INTRODUCTION

Bearing in mind that in the procedures of design of concrete in permanent contact with water considerations must establish to cover requests of service and low permeability in the first order and those of complementary resistance - stability mind. Across this work and with help of the ACI, which provides minimal requisites for the design and the construction of elements of concrete structurally with any structure, in this case quite what it concerns to the design and construction of Hydraulic Works.

1. CRITERIA OF HYDRAULIC DESIGN IN CHANNELS, SIPHONS AND AQUEDUCTS

1.1. CHANNELS

We will initiate classifying the diet of the channels:

- Diet CONTINUED – PERMANENT when the same expense happens in all his sections.

- VARIABLE diet: when they change the expenses.

- UNIFORM diet: when the speeds are the same, in this case the surface of the water and the rasante are parallel.

- INTENSIVE diet: when the slope of the channel is very strong the speed can be on the increase and diminish the water brace.

- SIMPLE-MINDED diet: when the slope is minor and the speeds become minors and therefore they increase the braces.

In the variable diets it can happen that the changes of expense increase and diminish in irregular form in this case the Diet is UNDULATORY. When it increases in regular form the diet it is INCREASING, a case of the natural willows.

a) ELEMENTS OF DESIGN OF A CHANNEL

The hydraulic design of the channels is defined according to three types of following elements:

Geometric elements

The brace in m a,dBreadth in the fund in m. b,fArea wetted in m2 APerimeter wetted in m. PRelation fund – brace XBreadth of the surface BBrace Criticized dc

Slope you rasp z:1Free rim in m fb

Kinetic elements

I spend in m3/seg QUnitary expense m3/seg/ml qAverage speed m/seg vPunctual speed m/seg w

Dynamic elements

Coefficient of Rugosity nHydraulic earring s

b) FORMULAE OF DESIGN OF CHANNELS

• Formulates of CHEZY

The formula OF Chezy modified by Darcy expresses itself:

H f=fL∗V 2

2gdSimplified it stays in:

V=C √r . sWhere:

s: hydraulic slope

C: it is a coefficient that depends on the radio hydraulically, of the coefficient of rugosity and of the slope.

• Formulates of MANNING

Manning simplifies the value of C, by means of experiments and expresses it:

C=r1 /16 /nand the speed has the following equation:

V=r2s∗S

12

nc) CRITERIA OF DESIGN

• Minimal Speed of Sedimentation.

The speed of the flow must not descend from certain low limit equivalent to the speed of deposition of the material in suspension that transports the water in the channel.

According to Robert Kennedy

U=b∗d0.64

Where: U, speed limits that it does not produce sedimentation.b, coefficient of sedimentation d, water brace.

• Maximum Speed of erosion.

The speed of the flow must not be major than that speed that it produces ravages in the walls and fund of the channel, damaging the revetments or modifying the outline of the natural river beds. In accordance with the material of the revetment some maximum speeds are:

Free sand 0.45 m/segI occur rarely with gravel 1.50 m/segI specify 4.40 m/segYou iron steel 12 m/seg

• Relation of Maximum Hydraulic Efficiency

In general the relation of M.E.H. is obtained when I remove hydraulic way is maximum and when the wet perimeter is minimal it expresses itself:

X=2.d (√1+z2−z )

• Coefficient of Rugosity

It is the resistance to the water flow that present the revetments of the artificial channels and the nature of the bed in the natural river beds.

C.E. Ramser of National Resourses Committe of U.S.A. makes possible the determination of the coefficients of the natural river beds by means of photography.

In the Handbook of hydraulics of King Horton it is possible to find the coefficients of rugosity for different types of revetments and states of conservation of the same one.

Some values:

Brick vitrificado 0.011Brushed Madeira 0.010I specify 0.012Big stones 0.030

Channels of ground 0.025Natural clean river beds 0.025River beds with vegetation 0.030

• Recommended Slopes

The inclination of the walls of the channels depends on the geology of the materials of excavation and filling for which it crosses.

• Recommended Slopes

The inclination of the walls of the channels depends on the geology of the materials of excavation and filling for which it crosses.

For courts of Slope

Conglomerate 1: 1 Clayish soils 1: 1Soils areno Lim. 1.5: 1Sandy soils 2: 1Sand soils S. 3: 1Shaken rock 0.5: 1Healthy rock ¼: 1

For fillings in:

Earth 1.5:1Sandy soils 3: 1

• Critical Braces

It depends on the type of section and they are the following ones:

Triangular:

dc=45

( v2

2 g+d )

Rectangular:

dc=23( v

2

2g+d )

Trapezoidal:

dc= 4 B5B+ f

v2

2 g

• Conditions of minimal infiltration

If it is desirable to obtain the minor possible loss of water for infiltration in the channels

X=4.d (√1+z2−z)

• Radios of Curvature Minimums

For the stakeout of the horizontal curves it is necessary to determine the radio of the curvature minimum, which is recommended I changed I bring in the following values:

Rc = 10d to 15d

Rc = 3B to 5B

The peraltamiento is calculated by the formula:

P=V2BgR

Where:

P: peraltamiento in m.B: breadth of the water mirror V: speed of the flowR: radio of curvature

• Free Rims

To give safety to the channel it is suitable to consider free rims in accordance with the brace and speed in the channel.

When the expense is minor of 2m3/seg a rim of 0.30m is sufficient.

If the wealth is major the Bureu of Reclamation uses for channels of supercritical diet the formula:

fb=0.60+0.0037 v3 x d1/2

Where

Fb, is the free rim.V, it is the speed.D, it is the brace.

1.2. ACUEDUTOS

The aqueduct is a conduit that flows as channel on a bridge and that serves to cross natural depressions or to spend a channel on a route (highway, line of train).

For the hydraulic design of this structure it is sufficient to change the section of the channel into a channel of rectangular section and to diminish his section to increase the hydraulic slope. With this object, after designing the most suitable section of the aqueduct, one determines the transitions of entry and exit to connect the section of the channel with the section of the aqueduct and respectively to the exit. The bridge must have sufficient height to allow to spend the agreed maxims of the river bed or allow to spend without mishaps the vehicle of more height that circulates in the route where it crosses the aqueduct.

1.2.1. COVERED CONDUITS.

The conduits covered are structures that serve to cross water courses under the natural river bed or are channels that go under the level of a route. 1.25 recommends to himself for these cases rectangular sections with a relation H/B =. The minimal recommended dimensions are H=1m and B=0.80m and in case of circular sections with a diameter of 0.75m. The covered conduits can be constructed of concrete armed and of steel. For the hydraulic design it was enough to calculate the most appropriate rectangular section and then the transitions of entry and exit that connect the channel of up-stream and the channel of streamwise.

1.2.2. THE INVERTED SIPHON

The inverted siphon is used equally with the same ends of the aqueduct, but in this case the channel rests on the hillsides of the depression and in case of a crossing with a route the channel happens below the same one, resting directly on the area.

The most recommended selections are also the rectangular section and the circular section, for which it is necessary to project transitions to connect the section of this structure with the section of the channels.

2.1. Hydraulic design

After having chosen the section of the siphon and calculating the corresponding transitions, the following losses of load are estimated:

a) Lost in the transitions of Entry and Exit They Are:

ht=kt(V s22 g−V c

2

2 g )❑

kt, in the entry 0.1kt, in the entry 0.2

b) Losses of load in grills

hr=kr ( SD )4/3

sen(V c22 g )c) Lost by friction in the transitions

hrt=( Sc+Ss2 )<¿

d) Lost by friction in the siphon

hrs=Ss∗ls

e) Lost by elbows

hs=0.25 V s2

2g∗√ o90 °

After calculating the losses, they all join and they add 10 % of the same ones to determine the difference of the rasantes.

The simbología is the following one:

ht = loss of load in the transitionVs = speed in the siphonVc = speed in the cannelH r = lost in the grills Kr = coefficient that depends on the section of the grills = thickness of the grillb = light between grills c = angle of the horizontal grillhft = loss of load for friction in transitionsSc = hydraulic slope channelSs = hydraulic slope siphonlt = length transition

hfs = lost by friction in the siphonls = length siphonhc = lost in elbows o = angle of deflection of the siphon

2. STRUCTURAL DESIGN OF HYDRAULIC WORKS

In the present work there appear some proper considerations of a structural project of the hydraulic works that will have to be born in mind for the design, supervision and construction of this type of works.

2.1. TYPES OF HYDRAULIC WORKS

Inside delos diverse types of hydraulic works can mention the preys, channels, siphons, aqueducts, reservorios supported and high, as it is possible to observe in the figures.

Each of the types of mentioned works has his peculiarities that must take in account when the design is carried out.

2.2. QUALITY OF CONCRETE CRACKING AND MEETINGS

One of the most important characteristics of the hydraulic works is the quality of the materials that were used, this often is more important than the same capacity to resist the efforts to which the structure will be submitted.

In accordance with the recommendations of the committee 350 of the ACI (Environmental Engineering Concrete Structures), one of the most important aspects that must fulfill the dosage of the concrete one is related to the maxim. Relation “ water / material cementante (a/c) ”, that is the best indicator to manage concrete of good performance.

Quality of Concrete

• Resistance of the Concrete one exposed to "severe" conditions f'c = 280min.• not exposed to severe conditions f'c = 245min • Maximum relation a/c = 0.45

Sanitary 'Normal' exhibition:

- When the liquids have a ph> 5 or it is exposed to solution of sulphates with less of 1500ppm.

Sanitary “ Severe ' exhibition: When the previous limits excel themselves.

In order to ' to achieve structures of concrete with a reasonable grade of impermeability and to guarantee that the steel of reinforcement does not have recubrimientos small, it is necessary to have present the following minimal dimensions in the elements of concrete:

Structural considerations Minimal thicknesses of walls - With h> 3 m. or more 30cm - With h <3 m. 15cm - With recubrimiento of 5cm or more than 20 cm- espacement maximum. Of reinforcement 30cm

In Peru, big part of the hydraulic works are located in the zone of the 'Saw', where the climate can be harmful, in these cases it is advisable to take in consideration the

recommendations of the Committee 306 of the ACI for cold climates. In general the air incorporation to the concrete one will allow to have more raincoats concrete; this is especially important for the cold zones.

Cold climate (ACI 306)

Cold climate is when for more than 3 consecutive days:

- The daily average of temperature of the air <5th C

- In 12 hours a day, the temperature of the air <10th C

' The daily average of temperature of the air is the average of the the biggest and the the most minor temperatures that happen during the midnight period to half a day ' (Between 12 pm and 12 m).

In cold climates, the temperature of the concrete one in the moment of his laying must be:

• Major to 13th C if the thickness of the elements is minor to 30 cm • Major to 10th C if the thickness is between 30 and 90 cm • Major to 7th C if the thickness is between 90 and 180 cm

To place ' Built-in Air '

Size of aggregation

Built-in air

1 ½”1” o ¾”

5 1/2 %6 %

The concrete one is a very good material as for his aptitude to resist efforts of compression, but in contrast also it has a problem that causes strong headaches to the engineers, I refer that during the process of hardening contracts. The restrictions, be of friction against the soil or because other elements it are prevented, they do not allow his free shrinkage from what generate important efforts of haulage that often produce crackings, especially when the draftsman did not evaluate the consequences of these effects.

Contraction of forge of the concrete one

Based on cured cylinders 28 days and then 50 á 60 % of moisture.

The high temperatures and the constructive inadequate process can produce crackings. The magnitude of the cracks will depend on the causes that produce them.

Efforts that cause cracking

The use of the fibers of polipropileno or another counterfoil polymer helps to diminish the thickness of cracks and fissures, in the following figures it is possible to observe his effectiveness.

TYPE PRINCIPAL CAUSES

TIME OF APPEARANCE

Plastic establishment.

Plastic contraction.

Thermal contractions.

Contraction of forge.

Excess of exudación

Dried rapid excessive

Heat and gradient of

temperature

Insufficient meetings

10 min – 3 hours30 min – 6 hours

1 day – 2 or 3 weeks

Several weeks or months

Cracking for plastic contraction of the concrete one

The fibers of polipropileno in the concrete one reduce the possibilities of cracking for plastic contraction.

In addition to indicating the dimensions and armed in the planes of the project, the best way of controlling the fissures is to design and to detail the meetings appropriately; nevertheless, it is frequent to observe that this does not happen and the result is negative, since the poor handling of the topic on the part of the draftsman leaves at freedom of action the Supervisor or Builder that if they do not have the necessary experience they can take inappropriate decisions. In some cases, this is the cause of the presence of fissures that they affect the final score of the project.

You join

Meetings of construction

At least it must spend 48 hours between both emptyings.

When it is possible "constructively", it is good to use mortar cement / sand / water equal to the concrete one but without thick aggregation.

Meetings of Dilation

• It is recommended 9 ' breaks waters> • The material selIador must allow an equal distortion the half of the meeting.

2.3. STRUCTURAL CONSIDERATIONS

Until a few years ago, the structural design of the channels of water conduction, reservorios and other hydraulic works it was carried out by the method of permissible efforts because it was considered that the ' method of break ' [whose name was worrying the not understood ones with the structural design, reason for which it changed for the so called one ' you load factorizadas ' or as meets him in his initials in Englishman LRFD (Praise and Resistance Factor Design)] was not offering the grade of sufficient impermeability to this type of works; nevertheless the factors of load it was. rum 'calibrated' to control the breadth of crack to 0.2 mm for structures submitted to

severe conditions of exhibition and of 0.25 mm for other hydraulic structures (for buildings there are allowed 0.4 mm for exterior works and 0.3 mm for interior works). This is achieved by the incorporation of a ' sanitary coefficient of durability ' that multiplies for the traditional factors of ' last load '

I design for charges factored

U = 1.7 H for propulsion of soilsU = 1.7 F for pressure of liquidsU = 1.4 D 1.7 L dead and alive load

To multiply 'U' for a ' sanitary coefficient of durability ':

- For reinforcement in push-up 1.30 U- For direct haulage 1.65 U- For for haulage. Diagonal 1.30 U- Zones of compression 1.00 U

I design for efforts of work

I specify: n=Es/Ec fc = 0.45 f'c Maximum recommended efforts Haulage 1,400 kg/cm2 Push-up (3/8 ', 1/2 ' and 5/8 ')

- For severe exhibition 1,550 kg/cm2 - For normal exhibition 1,900 kg/cm2

The minimal quantity by contraction and temperature is linked to the concept of the reinforcement needed to control the figuration produced by the forces that originate for the effect of contraction of forge united to the fact that the area presents a restriction to the free shrinkage of the concrete one, for such a motive this quantity will depend on big which is the element without meetings, as it is possible to observe in the following figure.

Minimal quantity for contraction and temperature

When the elements are thick, as the case of the small preys, this concept is applied to a superficial layer of 30 cm of thickness, which operates as one ' reinforced skin ' that it confines in a nucleus of concrete without arming. If the reinforcement meets in a face in permanent contact the area the values can reduce to the half.

Minimal quantity in thick sections of 60cm or more

50 % of the reinforcement in the ' low face ' of flagstones in contact with the area. For the design they are considered to be the charges that happen in an initial state of service; but simultaneously, it is necessary to foresee the situations of service that into some cases change the situations of work. For the design, in addition to the effect of the pressures it is necessary to consider to be the effects of cavitación and erosion who can suffer the elements for the particles in suspension in the water, it is for this reason that some structures will have to be ' lined superficially ' with stones blocks or metallic plates, since it is usual in case of the design of the ' spendthrifts of energy '.

Situations of design

Spendthrifts of energy Network of Flow

You force on a screen

Enlightenment of the forces that act in a prey.

For the design of the longitudinal reinforcement of the structures guy water channels, flagstones and other supported structures, when they become together much spread, owes to evaluate the force of haulage that takes place when it is a question of contracting the concrete one and the area offers resistance. Whereas to verify that slide does not take place between the wall of containment and the area uses the minimal values of coefficients of friction, for the design of the longitudinal reinforcement of the hydraulic structures there take the maximum values, which in some cases come up to ' 3 '.

The reinforcement calculated this way for elements of concrete with minor thicknesses to 60 cm they work out very similar for the obtained ones by ' minimal quantity '.

I reinforce to take the contractions of the concrete one.

Coefficient of friction ( )μ

2.4. HYDRODYNAMIC BEHAVIOR OF THE WATER AND SEISMIC DESIGN

It is important to understand the hydrodynamic behavior of the water. When it is inside a structure that contains them. For the supported reservorios the important thing takes root in the evaluation of the height of the swell to avoid the sub pressure

on the roofs or the effusion during an earthquake and for the raised structures the fundamental thing is to define that it departs from the water he accompanies to the movement of the reservorio as if it was an additional weight of the structure (fixed mass) and that it departs from the water has a free movement (mobile mass) and since it is possible to integrate to the seismic analysis of the structure.

Normative proposal for the Concrete ones Used in Hydraulic Works based on the International Norms ACI-350 and of Bureau Of Reclamation-USA.

1.-CONSIDERATIONS:

Having in consideration that in the procedures of design of concrete in permanent contact with water considerations must establish to cover requests of service and low permeability in the first order and those of complementary resistance - stability mind, there is proposed the inclusion of paragraphs of text in the Norm And 060 chapter 4 referred to requisites of durability of C ° To ° and the correspondent to Basic Information of the Norm You 100: Basic considerations of design of Sanitary Infrastructure of the National Regulation of Buildings (RNE), approved by means of D.S.N ° 011-2006-VIVIENDA in validity to the date, which they force to the public institutions to use concrete with designs that cover the basic characteristics of service needed as structures of conduction or temporary storage of raw water in his different presentations, clear, cloudy, with transport of sediments or organic proper material of the sewages and conditions of climatic severe exhibition.

Of this one it forms the public institutions of the country at national, regional and local level they will demand from his operative units of execution the making of technical internal rules characterized to the requests of service of the hydraulic work and conditions of climatic exhibition of the zone of influence of the project, which will be fulfilled by actions of implementation of minimal conditions of team and personal specializing technician for the design and securing of the concrete one of suitable resistances that prevent his rapid wear and obsoleteness, characteristic appellant to the date in the majority of evaluated works, propitiating the partial or entire deterioration in short periods of use, without they manage to expire in the majority of cases not even with 50 % of the period of established design committing an outrage against the profitability of the project and consistently in economic damage of the state.

Based on the identification of the causes that generate the rapid deterioration of the structures of concrete of the hydraulic projects of small and medium importance one concludes that these are generated on not having expired in strict form with the existing procedures of evaluation in the proposals of design, laying in work, control panel and periodic evaluation of damages for the development of activities of repair

and maintenance in accordance with a plan pre established with the allocation presupuestal corresponding, from what a strategic counterfoil of management has been prepared in his different phases of development in order these overcame problems based on the application of the recommendations of the national authors for the design, preparation, control and maintenance of the concrete one in this one type of works, which they must be characterized to the geographical, climatic environment and of constructive technology for the areas you will execute of the public institutions in our country, complemented with the norms and technical international recommendations for the design of concrete in contact with water of the ACI-350 and of the USBR.

The technical considerations demanded in the National Regulation of Buildings (RNE) for concrete in contact with water are of general character and they do not have imperative character, for example for concrete armed: Norm And 060 recounted to requisites of durability - chapter 4 the demand of requisites for concrete in exhibition to the water, on having included the term of: ' I specify that is claimed has low permeability ' that leaves to criterion of the draftsman his application, which procedure of analysis must be obligatory to everything structure that leads or stores water if the experience of performance is born in mind in works with concrete of resistances between 100 Kg/cm2 and 210 Kg/cm2 of common use in hydraulic works in our country and the normative reference established to countries with better operative and technological capacity as EE.UU, whose technical recommendations establish minimal resistances of the order of 4000 Lb/pg2. (283 Kg/cm2) to avoid crackings in this one type of concrete. Of equal form in the Norm You 100 recounted from basic considerations of design of sanitary infrastructure the draftsman is demanded to implement as basic information for forecast against disaster and other risks the report of evaluation of the vulnerability of the system and his components only opposite to emergency situations, must be obligatory for the conditions of use in contact with the diverse types of water, for the widespread partial destruction or whole of this one type of works in diverse zones of the country, caused for not having had the forecast of estimating characteristics of concrete that confront successfully requests of use, erosion of the drained or transported water including solid of dragging, organic material, chemical substances or changes of pressures.

From what it is necessary and essential to demand that the characteristics of the concrete one in works of conduction or water storage submitted to forces of friction and constant pressure will have to cover the expectations of conditions of use and outdoors as the importance of the project, prohibiting him that type of works to be executed this one by the national, regional and local governments and/or construction companies that have not previously in the zone of execution of the project of the equipment and the necessary conditions of securing of the type of concrete with the

quality and characteristics adapted to the service and climate of the zone established in the internal operative regulation of the area of institutional Infrastructure prepared based on experimental references, as the physical characteristics, chemistry and mechanics of the aggregations of the available quarries, of the area of empotramiento of the concrete one, of the water to use, I design of miscellanies, you try quality control and you would complement others; requirements and conditions that will have to be a part of the terms of reference properly quantified for the subscription of agreements for order or the base formulation for the awarding of works for contract or internal regulation for the execution of works for direct administration. With these actions one tries to establish the obligatory fulfillment of procedures of design in the different phases of making of the studies that sustain and serve as base to formulate the records of execution of the hydraulic works in the country, allowing the economic evaluation of structural components of concrete simple and/or armed with major initial cost, taking a major durability as a compensation in the horizon of design which incidence will have to be reflected in the results of the prosecution of calculation of the flow of investment of the project when the studies prepare of pre investment determining his viability based on the economic indicators of profitability of the economic evaluation of PIP, allowing the attainment of a hydraulic durable and efficient work during the period of established design, characteristics that are obtained on having used appropriate materials that guarantee the durability opposite to the predominant requests of use and service and where the interaction prevails between the hydraulic proposed structure and the natural and anthropomorphic characteristics of the environment.

2.-METHODOLOGY

The used methodology understands four phases; Identification of the problem, causes and effects; technical Compilation of the frame of reference existing in the country; Implementation of a counterfoil of strategic - operative management in the different phases of formulation and execution of the hydraulic project, for the securing of the concrete one that expires with the requisites of service and low permeability that are parameters of supreme importance in structures in permanent contact with water in his different presentations, complementarily to those of resistance and stability demanded habitually for any structure and finally to test the normative enclosing proposal to the RNE, taking as a reference recommendations and national and international rules conditioned to the installed and technological capacity with which there are provided our institutions public and deprived in the country to develop this type of works.

2.1. Identification of frequent problems and the causes that provoke it in the structures of concrete of hydraulic works constructed in diverse zones of the country.

2.1.1. In the stage of Planning

a) Hydraulic projects with structural components of concrete of low resistance that they spoil partially or completely in the first years of service; problem and effect generated by the following causes:

1) Absence in local and regional diagnoses of performance of service of the hydraulic works constructed by the public institutions based on annual reports of the entity user.

2) Inexperience of the formuladores of studies of Pre investment.

3) Nonexistence of studies of hydraulic simulation that would allow to know the fluvial behavior of the rivers in the diverse regions of the country, his characteristics that are very varied, his stability, the dimensionamiento and design of structural and not structural works to keep her stable in the time.

4) Nonexistence of works of risks and vulnerability of fluvial origin.

b) Incidence in the partial destruction or whole of the hydraulic works in the first years of service for erosion or destabilization caused by the transported solid ones consisting of materials of fund, saltación and suspension; problem and effects caused by the following causes:

1) Insufficient number of stations of measurement hidrométrica, pluviométrica, of transport of sediments, seismic and others in the zone in study.

2) Inadequate treatment and application of the information hidrológica obtained.

3) Nonexistence of a cadaster and record of information of compatibilización of parameters of design used in the diverse structures of capture constructed in the zone, using them as stations of obligatory control and the extreme events produced so much in droughts as in avenues.

c) There do not develop plans of operation and maintenance in accordance with the conditions of functioning of the hydraulic structures, causing his rapid destruction; problem and effect caused by the following cause:

1) The absence of precise terms of reference and presupuestados for the making of this one type of studies of operation and maintenance, so much in the stages of pre investment as of investment and the almost void habitualidad of developing them for the public institutions in works of small and medium importance.

2.1.2. In the stage of Design

a) The technical specifications of the records for the execution of hydraulic works conditions of service do not contemplate characteristics of the low concrete one with water, which demands low permeability what it would force to fulfill with minimal parameters in the design of miscellanies as a/c relation, establishment of miscellany, resistances to compression, processes of miscellany, cured special, etc.; problem caused by the following causes:

1) The norm for sanitary works does not contemplate requisites for concrete in contact with water in his diverse types of presentation.

2) The public local and regional Institutions do not develop internal specific regulations for this one type of works.

b) The hydraulic structures do not expire with the period of established design, shortcoming generated by the following causes:

1) They are not fulfilled by the minimal requisites of design referred to resistance, stability, service and low permeability.

2) Studies do not develop in detail of the risk and vulnerability.

3) Plans of risk are not established for contingencies.

2.1.3. In the stage of Construction

a) The hydraulic structures deteriorate in the first years of partial service or completely, problem generated by the following cause:

1) Nonexistence of recommendations of constructive character similar to the existing one in the international regulation for the resistance of the concrete one in contact with the water, so much for big and small hydraulic works (USBR. ACI).

2.1.4. In the stage of Operation and Maintenance

a) The hydraulic structures do not expire with the period of established design, shortcoming generated by the following cause:

1) Nonexistence of plans and formulation of manuals of operation and maintenance corresponding to the diverse structures and components that shape a hydraulic work.

2) Lack of terms of reference and norms that determine contractual obligations for the formulation of operative plans of the professionals responsible for the planning, design and construction of hydraulic projects.

3.-YOU INDEX

3.1. Graphic references of effects of the treated problems:

Photo Nº 1

Photo Nº 2

Ref. Photo Nº 1 and 2. Typical problems of rupture, erosion and wear in structure of concrete in works of derivation and capture of small and medium hydraulic projects executed in the zone it saws.

Photo Nº 3 Photo Nº 4

Ref. Photo Nº 3 and 4. Typical problems of early obsoleteness of the concrete one in hydraulic works for conditions of exhibition in the zone forest that they generate weakening of the structure and filtrations.

3.2. Normative existing reference in Peru for the Concrete one used in Hydraulic works

National regulation of Buildings (RNE)

Norm and 060 I Specify Armed

Chapter 4 Requisites of Durability

Norm you 100 basic Considerations of design of infrastructure Sanitary

3.3. Normative International existing reference to the Concrete one used in Hydraulic Works

3.3.1. AC1.350R.89 - ACI.350.06: Environmental Engineering Concrete Structures.

In short the norm ACI-350 in his publications checked the year 1989 and 2006 implements basic recommendations for the structural design of hydraulic works that commonly is used to contain industrial or domestic water or for water treatment of waste, needing the dense and impermeable concrete one from him, with a high resistance to the attack of chemical products. Taking in account that the possibility of cracking is minimized, espaciamiento between meetings, indicating him the

proportions that must have the miscellany of concrete, his gatecrasher, the cured one and protection from chemical products, indexing his recommendations to norms as the ACI 318, ACI 223, ACI 224 between others.

The principal properties of the hydraulic sanitary structures designed with the considerations established in the norms ACI 350 and the USBR they are:

a) Extremely impermeable to minimize the contamination of the supplying of the water or environmental.

b) They provide the maximum resistance to the attack of chemical substances.

c) They provide smooth surfaces in order to minimize the resistance to the flow.

With what they are fulfilled by the minimal conditions of design that must have the hydraulic structures of sanitary use, conduction, water storage of diverse characteristics and riverside defense, referred to service (durability) and low permeability.

In accordance with the recommendations of the Committee 350 of the ACI (Environmental Engineering Concrete Structures), one of the most important aspects that must fulfill the dosage of the concrete one is related to the maximum relation ' water / material cementante (a/c), that is the best indicator to manage concrete of good performance. A way of achieving this relation ' a/c ' in an indirect way is to use concrete of high resistance, not because it is needed, but rather because, on having dosed concrete these, it is guaranteed that the relation 'a/c' is low.Therefore the quality of concrete will have the following characteristics and conditions of use.

Quality of Concrete:

- Resistance of the concrete one exposed to severe conditions: l ' c=280Kg/cm2 (mín.).

- Resistance of the concrete one exposed to normal conditions: f ' c=245Kg/cm2 (mín.).

Conditions of exhibition:

- Normal

When the liquids tienenun ph> 5 or it is exposed to solution of sulphates with less than 1500 ppm.

- Severe

When the previous limits excel themselves.

3.3.2. USBR: Design of Small Canal Estructures

In short the norm of structural design of small channels of the Bureau of Reclamation (USA) ACI-350 in his publications checked from the year 1995 implements basic recommendations for the hydraulic, structural design and of stability of small channels for water conduction with standardized sections which wealth of transport is limited 100 pie3 / century (2.83 m3/s.), being the concepts and tackled methods applicable to slightly major structures.

The principal properties of the channels and hydraulic structures designed with the considerations established in the norms of the USBR are:

a) The methodology used in the hydraulic design, provides of suitable capacity of discharge for the structures aligned with the channel, a suitable dissipation of energy and minimal losses of load.

b) The methodology used in the structural design, provides thicknesses of concrete and reinforcements of piece of metal to resist the efforts under reasonable charges on the structures.

c) The methodology used in the design of stability, provides suitable dimensions of the structures to resist the slide and the volteo, to prepare that the water of percolación removes the material of the foundation and that the pressures are minor that the authorized ones.

With what they are fulfilled by the minimal conditions of design that must have the hydraulic structures of sanitary use, conduction, water storage of diverse characteristics and riverside defense, referred to resistance stability, service (durability) and low permeability.

In accordance with the recommendations of the USBR, it is necessary to use in the construction of the hydraulic structures of water conduction concrete with the following resistances in function to the methods of design used.

Method of the effort of the work:

Resistance of the concrete one to 28 days: f ' c = 4,000 Lb/pg2 = 283 Kg/cm2 (mín.).

Resistance of the reinforcement of steel: f ' and = 60,000 Lb/pg2 = 4,241 Kg/cm2 (mín.).

Permissible effort of compression to the concrete one: f'c = 1,800 Lb/pg2 = 127 Kg/cm2 (mín.).

Permissible effort of compression of the reinforcement of steel: l ' and = 24,000 Lb/pg2 =1, 696 Kg/cm2 (mín.).

Method of the last effort:

Used for prefabricated tubes of pressure of concrete armed.

Resistance of the concrete one to 28 days: f ' c = 4,500 Lb/pg2 = 318 Kg/cm2 (mín.).

Resistance of the reinforcement of steel: f ' and = 40,000 Lb/pg2 = 2, 827 Kg/cm2 (mín.).

4.-Counterfoils of strategic operative management for the securing of concrete of low permeability and ideal serviciabilidad in hydraulic projects

Based on the field evaluations realized so much in the zone saw and forest in hydraulic works of small and medium importance and the diagnosis of the causes that provoke her, has prepared the picture counterfoil of management strategically - operative basic in the different stages of planning and attainment of this type of works, with the purpose of which they manage to cover the expectations of design in the period of obsoleteness established for his diverse components corresponding to durability and efficiency in the function that they redeem in the integral project, the pictures counterfoils presented are complementary to the recommended ones to use in any hydraulic project.

STRATEGIC AXES OF OBLIGATORY DEVELOPMENT IN A HYDRAULIC PROJECT

- Planning - Design - Construction - operation

- Maintenance

4.1. In the phase of Planning and Design

4.2. In the phase of CONSTRUCTION

4.3. In the phase of OPERATION AND MAINTENANCE

TECHNICAL SAFETY REQUIREMENTS (MDEQ) - ACI 350-06

1. STRUCTURAL DESIGN

The technical requirements presented in this chapter are minimum requirements set by MDEQ Dam Safety. The majority of the requirements in this chapter come from ACI 350-06. Additional guidance for structural design can be found in the documents listed below.

AVAILABLE GUIDANCE:

AMERICAN CONCRETE INSTITUTE (ACI)

ACI 318-08 or most recently adopted edition: Building Code Requirements for

Reinforced Concrete

ACI 350-06 or most recently adopted edition: Code Requirements for Environmental

Engineering Concrete Structures

PORTLAND CEMENT ASSOCIATION

Rectangular Concrete Tanks

NATURAL RESOURCES CONSERVATION SERVICE (NRCS or SCS)

Technical Release No. 5: Structural Design of Underground Conduits

Technical Release No. 18: Computation of Pipe Joint Extensibility Requirements

Technical Release No. 30: Structural Design of Standard Covered Risers

Technical Release No. 31: Structural Analysis and Design at Low Stage Inlets

Technical Release No. 37: Structural Analysis and Design at Base of Riser with Conduit

Openings in Both Endwalls

Technical Release No. 42: Single Cell Rectangular Conduits, Criteria and Procedures for

Structural Design

Technical Release No. 45: Twin Cell Rectangular Conduits, Criteria and Procedures for

Structural Design

Technical Release No. 50: Design of Rectangular Structural Channels

Technical Release No. 54: Structural Design of SAF Stilling Basins

TRN 54-1: 1981 Update to Wingwall Design

Technical Release No. 63: Structural Design of Monolithic Straight Drop Spillways

Technical Release No. 67: Reinforced Concrete Strength Design

Technical Release No. 74: Lateral Earth Pressures

National Engineering Handbook, Section 6: Structural Dams

National Engineering Handbook, Section 11: Drop Spillways

National Engineering Handbook, Chapter 52: Structural Design of Flexible Conduits

U.S. ARMY CORPS OF ENGINEERS

EM 1110-2-2104: Strength Design for Reinforced Concrete Hydraulic Structures

EM 1110-2-2104: Change 1, 20 Aug 03

EM 1110-2-2902: Conduits, Culverts, and Pipes

EM 1110-2-2100: Stability Analysis of Concrete Structures

AMERICAN IRON AND STEEL INSTITUTE

Welded Steel Pipe Design Manual, 2007 or most recent edition

AMERICAN WATER WORKS ASSOCIATION

Steel Pipe-A Guide for Design and Installation (Manual of Water Supply Practices M11)

U.S. BUREAU OF RECLAMATION

Guide to Concrete Repair

Design of Small Dams

Engineering Monograph No. 27: Moments and Reactions for Rectangular Plates

AMERICAN SOCIETY OF CIVIL ENGINEERS

ASCE 7-10: Minimum Design Loads for Buildings and Other Structures

CONCRETE REQUIREMENTS

In general, concrete and reinforcement used in spillways and ancillary structures, shall meet the requirements of ACI 350-06, Code Requirements for Environmental Engineering Concrete. Structures or most recent edition.

The minimum compressive strength of concrete used in any part of construction of a dam or outlet works shall be 4,000 psi. Concrete that is to be subjected to abrasion erosion shall meet the requirements of ACI 350-06, Section 4.6.3. Concrete that is subjected to freeze-thaw conditions shall meet the requirements of ACI 350-06, Section 4.2.

Reinforcement shall be ASTM A 615 (Billet Steel), Grade 60.

The minimum concrete cover for reinforcing steel shall be in accordance with ACI 350 06, Section 7.71.

The minimum distance between primary flexural reinforcement shall not exceed the lesser of 12 inches or that determined by the requirements given in ACI 350-06, Section 10.6.5. Minimum flexural reinforcement shall be determined by ACI 350-06, Section 10.5.1.

All exposed concrete surfaces shall have a Class C or better finish. .Joints shall be designed in accordance with ACI 350.4R-04: Design Considerations for Environmental Engineering Concrete Structures, Chapter 5. Waterstops shall be required in all joints.

Minimum shrinkage and temperature reinforcement shall be in accordance with ACI 350-06, Section 7.12.

Aggregates proposed for use in concrete structures associated with High and Significant Hazard dams shall be tested for Alkali-Silica Reactivity.

RIGID CONDUITS

In general, cast in place conduits should be designed in accordance with EM 1110-2-2104 along with guidance presented in ACI 350-06.

Joints in rigid conduits must be designed to be watertight and flexible to accommodate longitudinal and lateral movements. The specifications should contain a requirement that joints be hydrostatically or air tested prior to backfilling around the conduit.

Circular concrete pressure pipe should conform to and be installed in accordance with EM1110-2-2902, Chapter 3, Section 3-1 to 3-3 (see Page 94 Conduits through embankment dams). It must also be AWWA 300, 301, or 303 pipe. 4

The outside walls of concrete box culverts shall have a 1H:10V or more side slope for improved compaction of earthfill against the conduit.

Concrete cradles are required for circular conduits on all high and significant hazard dams and should be designed in accordance with NRCS Technical Release No. 5 or most recent NRCS guidance. Foundations for conduits shall be reviewed and approved by Geotechnical Engineer.

Cast in place conduits shall be constructed in alternating sections with control joints which include water stops that are either dumbbell or ribbed with a centerbulb.

Computation of joint extensibility requirements shall be performed and implemented for all conduits constructed on yielding foundations. Guidelines can be found in NRCS’s Computation of Joint Extensibility Requirements (1969).

Cast in place conduits through embankments should be designed and constructed with a camber to allow positive drainage. The camber should be computed based upon the maximum anticipated settlement of the embankment.

Filter diaphragms shall be used to limit the potential of piping for any conduit penetrating though the embankment. Guidelines can be found in NRCS’s National Engineering Handbook, Part 628 Dams, Chapter 45 Filter Diaphragms.

FLEXIBLE CONDUITS

In general, Steel pipe shall be designed and installed in accordance with AWWA M11, Steel Pipe – A Guide for Design and Installation and Chapter 52 of the National Engineering Handbook, Structural Design of Flexible Conduits and Plastic pipe shall be designed in accordance with FEMA Technical Manual: Plastic Pipe Used in Embankment Dams (FEMA P-676) and Structural Design of Flexible Conduits.

Corrugated Metal Pipe (CMP) is expressly prohibited in all new high and significant hazard dam construction.

Computation of joint extensibility requirements shall be performed and implemented for all conduits constructed on yielding foundations. Guidelines can be found in NRCS’s Computation of Joint Extensibility Requirements (1969).

Joints in flexible conduits must be designed to be watertight and flexible to accommodate longitudinal and lateral movements. The specifications should contain a

requirement that joints be hydrostatically tested prior to backfilling around the conduit.

SPILLWAY SLABS

Spillway slabs should be designed to meet applicable factors of safety for uplift, sliding and foundation reaction. Guidelines for stability analyses can be found in USACE EM 1110-2-2100.

Spillway slabs should be a minimum of 8” thick with a minimum temperature and shrinkage reinforcement of #4 bars at 12” on center in each face unless additional reinforcement is required by ACI 350-06, Section 7.12 or spacing of reinforcement is limited by ACI 350-06, Section 10.6.5.

All spillway slabs on the downstream face of a dam shall be underlain with a sand filter to collect any seepage that may occur behind the slab or leakage through joints. The sand filter should have perforated drain pipes of a minimum of 4” in diameter to collect seepage and convey it downstream of the dam.

All joints shall have water stops that are designed in accordance with ACI 350.4R-04: Design Considerations for Environmental Engineering Concrete Structures, Chapter 5.

Typically, dumbbell waterstops are utilized for non-moveable joints (i.e. construction joints) and centerbulb waterstops are utilized for moveable joints (i.e. expansion/contraction joints).

RISERS

All risers should be checked for flotation as follows (from SCS TR 30):(1) When the riser is located in the reservoir area, the ratio of the weight of the riser to the weight of the volume of water displaced by the riser shall not be less than 1.5. Low stage inlet(s), if any, shall be assumed plugged for this computation.

(2) When the riser is located in the embankment – same as (1), but add to the weight of the riser, the buoyant weight of the submerged fill over the riser footing projections. Take the buoyant unit weight as wb = 50 pcf.

Note: Flexible risers and conduits may need to be embedded in a concrete base to prevent flotation. A spreadsheet for performing this calculation can be obtained from the MDEQ Dam Safety Division.

APPURTENANT STRUCTURES FOR DAMS (SPILLWAYS AND OUTLET WORKS) DESIGN STANDARDS

1.1 Purpose

The design standards present clear and concise technical requirements and processes to enable design professionals to prepare design documents and reports necessary to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public. Compliance with these design standards assists in the development and improvement of Bureau of Reclamation (Reclamation) facilities in a way that protects the public's health, safety, and welfare; recognizes all stakeholder needs; and achieves the lasting value and functionality necessary for Reclamation facilities. The responsible designer(s) accomplishes this through processes that enable compliance with these design standards and all other applicable technical codes, as well as incorporation of the stakeholder’s vision and values, that are then reflected in the construction project.

1.2 Application of Design Standards

All Reclamation design work, whether performed by the Technical Service Center (TSC), the regional offices, or an architectural/engineering (A&E) firm, will conform to the design standards. Reclamation’s use of its design standards requires designers to also integrate sound engineering judgment with applicable national standards, site-specific technical considerations, and project-specific considerations to ensure suitable designs and protect public safety. The design standards are not intended to provide cookbook solutions to complex engineering problems. Strict adherence to a handbook procedure is not a substitute for sound engineering judgment. The designer should be aware of and use state-of-the-art procedures. Designers are responsible for using the most current edition of referenced codes and standards and to be aware that Reclamation design standards may include exceptions to requirements of these codes and standards.

1.3 Deviations and Proposed Revisions

Design activities must be performed in accordance with established Reclamation design criteria, Reclamation engineering, architectural, or technical standards, and approved national design standards. Exceptions to this requirement will be DRAFT - Design Standards No. 14 - Appurtenant Structures for Dams (Spillways and Outlet Works) Design Standards 1-2 DS-14(1)-2 March 2010 pursued in accordance with provisions of Reclamation Manual Policy, Performing Designs and Construction Activities, FAC P03. Reclamation designers should inform the TSC, via the Web site notification procedure, of any recommended updates or changes for the design standards to meet current design practices.

1.4 Scope

Design Standard No. 14 provides technical guidance concerning Reclamation’s procedures/considerations for analyzing/designing two key appurtenant structures associated with dams and/or dikes. These appurtenant structures are spillways and outlet works. Chapter 1 provides an overview for the analysis/design of spillways and outlet works, while the following chapters provide detailed procedures/considerations that should be followed by Reclamation staff and others involved with analyzing/designing modifications to and/or new spillways and outlet works. It should be stressed that this design standard will not duplicate other existing technical references but, wherever possible, it will reference existing procedures/considerations that should be used for the analysis/design of spillways and outlet works.

1.5 Definitions

The following definitions are provided to clarify the terminology used in Design Standard No. 14. These definitions are consistent with other technical references used by Reclamation.

1.5.1 Spillway

A spillway is a hydraulic structure that passes normal (operational) and/or flood flows in a manner that protects the structural integrity of the dam and/or dikes (reservoir impoundment structures). Spillways are hydraulically sized to safely pass the Inflow Design Flood (IDF).2. The IDF will be equal to, or less than, the Probable Maximum Flood (PMF).3 For more details and guidance about floods, refer to Chapter 2, “Hydrologic Considerations.”

1.5.1.1 Service Spillway

A service spillway provides continuous or frequent regulated (controlled) or unregulated (uncontrolled) releases from a reservoir without significant damage to the dam, dike, or appurtenant structures due to releases up to and including the design discharge. Service spillways are illustrated in figures 1.5.1.1-1 and 1.5.1.1-2.

1.5.1.2 Auxiliary Spillway

An auxiliary spillway is infrequently used and may be a secondary spillway which is operated sparingly. During operation there could be some degree of structural amage or erosion to the auxiliary spillway due to releases up to and including the design ischarge. Auxiliary spillways are illustrated in figures 1.5.1.2-3 and 1.5.1.2-4.

1.5.1.3 Emergency Spillway

An emergency spillway is designed to provide additional protection against overtopping of a dam and/or dike and is intended for use under extreme conditions such as misoperation or malfunction of the service spillway or other emergency conditions or during very large, remote floods (such as the PMF). As with auxiliary spillways, some degree of structural damage and/or erosion would be expected due to releases up to and including the design discharge. Emergency spillways are illustrated in figures 1.5.1.3-5 and 1.5.1.3-6.

1.5.2 Outlet Works

Outlet works consist of a combination of features (i.e., intake structure, conveyance features such as conduits, control structure, etc.) and operating equipment (electrical and mechanical) required for the safe operation and control of water released from a reservoir to meet downstream needs. The outlet works serves various purposes such as regulating streamflow and water quality; releasing floodwater; power generation; emergency evacuation; and providing irrigation, municipal, and/or industrial water. Features of outlet works are illustrated in figure 1.5.2-7.

1.6 Configurations

There are some common/typical and unique configurations (features) associated with spillways and outlet works. These features are further discussed in the following sections.

1.6.1 Spillway

Generally speaking, features common to most spillways are illustrated in figure 1.6.1-8 and include:

• Approach channel and safety/debris/log boom.

• Control structure, such as crest structure or grade sill, and gates,

bulkheads, stoplogs, along with associated operating equipment.

• Conveyance features, such as chute floor and walls and/or

conduit(s)/tunnel(s).

• Terminal structure, such as hydraulic jump stilling basin, flip bucket,

plunge pool, etc.

• Downstream channel.

1.6.2 Outlet Works

Features common to most outlet works are illustrated in figure 1.6.2-19 and include:

• Intake structures, trashracks, gates/valves, and bulkheads (if appropriate).

• Conveyance features, such as conduit(s)/tunnel(s).

• Control structure, such as gate chamber, gates/valves, access shaft/adit/conduit, along with operating equipment.

• Terminal structure, such as hydraulic jump stilling basin, impact structure, plunge pool, etc.

• Downstream channel. Considerations that should be used, unless there is justification to deviate, include:

• Two gates or valves in series should be installed and operated in Reclamation outlet works. The downstream gate or valve provides regulating capabilities, while the upstream gate or valve provides emergency closure capabilities under unbalanced head (flow) conditions, or routine closure capabilities under balanced head (nonflow) conditions.

• Although common throughout the water resource engineering industry, constructing an outlet works through/beneath an embankment dam and/or dike should be viewed as a second choice (i.e., avoid/limit contact/interface between the conduit and embankment). A preferred alternative to minimize internal erosion potential is to construct a tunnel outlet works through the dam and/or dike abutment or through the reservoir rim.

Another aspect of outlet works configuration relates to the location of hydraulic control (i.e., the location of the regulating gate or valve). The four configurations [1]5 typically used by Reclamation are illustrated in figures 1.6.2-20 through 1.6.2-23 and include the following:6,7

• Preferred configuration. Hydraulic control at intake with free flow conditions downstream of the regulating gate or valve. Most often used for low head applications in embankment dams where pressurized flow is not required at the downstream end of the outlet works. When the outlet works is not being operated, there is access for inspection and maintenance through the entire length of the conduit (figure 1.6.2-20).

• Preferred configuration. Hydraulic control at downstream control structure, with guard/emergency gate/valve at/near centerline of dam/dike, and downstream pressurized pipe (between dam/dike centerline and control structure) inside larger access conduit. Applicable for power generation or pressurized downstream flow. During both operation and nonoperation of the outlet works, there is excellent access for inspection and maintenance through downstream conduit (figure 1.6.2-21).

• Acceptable configuration. Hydraulic control at/near the dam/dike centerline with free flow conditions downstream of the regulating gate or valve. When the outlet works is not being operated, there is access for inspection and maintenance through the downstream conduit (figure 1.6.2-22).

Least acceptable configuration. Hydraulic control at the downstream end of the outlet works, which may be near the downstream toe or face of the dam/dike (i.e., pressure flow conditions upstream of the regulating gate or valve along most of the outlet works). Commonly used in concrete dams. Accessibility for inspection and maintenance is limited (underwater inspection) without bulkheading upstream intake structure or draining the reservoir.

1.7 Design Procedures/Considerations

Details of analysis/design procedures/considerations will be provided in the following chapters of Design Standard No. 14. An overview is provided in the following text of this chapter. Analysis and/or design (including both new and modification) for a spillway and/or outlet works will typically follow a number of key procedural guidelines including:

• Design data collection guidelines [2].

• Feasibility design guidelines [3].

• Final design process [4].

• Cost estimating [5].

• Safety of Dams project management guidelines [6].

1.7.1 Spillway Design/Analysis

Tasks for analyzing/designing spillways are summarized in the following

sections.

1.7.1.1 Location, Type, and Size Selection of the location, type, and size of a spillway will be dependent on the evaluation of a number of factors including:

• Site conditions (geology/topography).

• Dam and/or dike type.

• Hydrologic considerations.

• Hydraulic considerations.

• Seismic considerations.

• Construction/constructability considerations.

• Project objectives.

• Robustness of design.

• Risks associated with Plausible Potential Failure Modes (PFMs),

which must be tolerably below Reclamation’s public protection guidelines.

• Operation and maintenance considerations.

• Economics.

These factors are further discussed in the following chapters of this design standard and some of the following sections. Two factors that should be highlighted, which are somewhat unique to Reclamation facilities, are the robustness of design and the risks associated with PFMs. Because many of the spillways are associated with significant and high hazard dams/dikes, it is important that any new or modified appurtenant structure designs protect the public to levels consistent with Reclamation’s public protection guidelines [7] (i.e., maintain and/or reduce risks to acceptable levels). This could mean some redundant features/equipment and designing to stricter requirements than commonly called for by professional codes, standards, and/or guidelines. For more detailed guidance associated with locating, along with selecting, a type and size of a spillway, refer to Chapter 3, “General Spillway Design Considerations.”

1.7.1.2 Hydraulic Analysis/Design

The hydraulic analysis/design will be concurrent with the previous task of locating and selecting a type and size of spillway. The following chapters of this design standard explain the steps of hydraulic analysis/design, including:

• Develop/verify discharge curves.

• Prepare initial flood routings of frequency floods up to the PMF to verify the appropriateness of the spillway type and size, and to select the IDF.

• Refine spillway control (crest) structure layout and associated discharge curves based on results from previous steps. DRAFT - Chapter 1 - Introduction

DS-14(1)-2 March 2010 1-9

• Prepare final flood routings to estimate maximum reservoir water surfaces (RWS) and discharge ranges for various floods and operational conditions (part of the final flood routings will include a freeboard assessment, which is sometimes referred to as a robustness study).

• Prepare initial water surface profiles to lay out the spillway conveyance features and terminal structure size and type.

For more detailed guidance associated with hydrologic and hydraulic analysis/design for a spillway, refer to Chapter 2, “Hydrologic Considerations,” and Chapter 5, “Hydraulic Considerations.”

Technical references associated with the hydraulic analysis/design of spillways include:

• Design of Small Dams, third edition [8].

• Engineering Monograph (EM) No. 9 – Discharge Coefficients for Irregular Overfall Spillways [9].

• EM No. 25 – Hydraulic Design of Stilling Basins and Energy Dissipators [10].

• EM No. 42 – Cavitation in Chutes and Spillways [11].

• Reclamation – Engineering and Research Center (REC-ERC)-73-5 – Hydraulic Model Studies of Chute Offsets, Air Slots, and Deflectors for High-Velocity Jets [12].

• REC-ERC-78-8 – Low Froude Number Stilling Basin Design [13].

• REC-ERC-85-7 – Hydraulic Model Studies of Fuseplug Embankments[14].

• REC-ERC-88-3 – Overtopping Flow on Low Embankment Dams – Summary Report of Model Test [15].

• Dam Safety Office (DSO)-07-07 – Uplift and Crack Flow Resulting from High Velocity Discharges Over Offset Joints [16]. DRAFT - Design

Standards No. 14 - ppurtenant Structures for Dams (Spillways and Outlet Works) Design Standards 1-10 DS-14(1)-2 March 2010

• Assistant Commissioner – Engineering and Research (ACER) Technical Memorandum (TM) No. 10 – Guidelines for Using Fuseplug Embankments in Auxiliary Spillways [17].

• Hydraulic and Excavation Tables, 11th edition [18].

• Computing Degradation and Local Scour [19].

1.7.1.3 Foundation Analysis/Design

The foundation analysis/design will start when a tentative type and size of spillway is located and selected, and it parallels the structural analysis/design efforts. The following chapters of this design standard explain the steps of foundation analysis/design, including:

• Define site-specific foundation material and strength properties.

• Assist in identifying suitable sites based on site-specific foundation needs

for a spillway.

• Define and analyze ground water conditions.

• Develop appropriate foundation designs which include: o Drainage features such as underdrains, slope drainage, and filters (NOTE: Identify and evaluate drainage features/systems that will be accessible for inspection using closed circuit television (CCTV) equipment).

o Adequate support for the spillway, which could range from excavating

to competent rock to driving piles or placing piers in a soil foundation.

1.7.1.4 Structural Analysis/Design

The structural analysis/design of the spillway typically follows the hydraulic analysis/design. The following chapters of this design standard explain the steps of structural analysis/design, including:

• Identify which features are considered “critical”8 and “noncritical.”.

• Identify and define loading conditions for both critical and noncritical

features, which will typically fall into four categories, including:

o Construction.

o Operational (normal or static).

o Flood (hydrologic).

o Earthquake (seismic).10

• Identify, evaluate, and select material types and associated properties.

Materials could include concrete (reinforced, conventional mass, roller compacted, and precast), steel, and plastic such as high-density polyethylene (HDPE).

• Apply appropriate structural analysis/design methods, which are based on the crawl, walk, and run philosophy (i.e., using the simplest approach that is technically adequate to prepare the analysis/design). These include:

o For analyses. Pseudo-static, linear elastic finite element modeling

(FEM), using response spectra, and nonlinear elastic FEM, using time

histories, are employed to analyze a structure.

o For designs. Design methods are typically based on Reclamation

technical references, such as Design of Small Dams [8], and industry

codes are used, such as the American Concrete Institute (ACI)

manuals. For more detailed guidance associated with structural analysis/design for a spillway, refer to Chapter 7, “Structural Considerations.”

Technical references associated with the structural analysis/design of spillways include:

• Design of Small Dams, third edition [8].

• EM No. 14 – Beggs Deformeter-Stress Analysis of Single-Barrel Conduits [27].

• EM No. 14 Supplement – Beggs Deformeter-Analysis of Additional Shapes [28].

1.7.2 Outlet Works Design/Analysis

Tasks for analyzing/designing outlet works are summarized in the following sections.

1.7.2.1 Location, Type and Size

Similar to the spillway, selection of the location, type, and size of an outlet works will be dependent on the evaluation of a number of factors including:

• Site conditions (geology/topography).

• Dam and/or dike type.

• Hydrologic considerations.

• Hydraulic considerations.

• Seismic considerations.

• Construction/constructability considerations.

• Project objectives.

• Robustness of design.

• Risks associated with credible PFMs, which must be tolerably below

Reclamation’s public protection guidelines [7].

1.7.2.2 Hydraulic Analysis/Design

Similar to the spillway, the hydraulic analysis/design will be concurrent with the previous task of locating and selecting a type and size of outlet works. The following chapters of the design standard explain the following steps of hydraulic analysis/design:

• Develop/verify discharge curves.

• Evaluate intake structure and conveyance features (such as conduit) sizes,

along with gate/valve types/sizes based on:

o Diversion. If outlet works will be used for diversion during

construction, initial flood routings of diversion floods (sometimes

referred to as construction floods) should be done to size conveyance

features and temporary cofferdams.

o Normal operations. Evaluate conveyance features size and

gate/valve type/size for passing operational flows.

o Emergency evacuation. Evaluate ability of outlet works to lower the

reservoir in a timely fashion pursuant to guidelines noted in Criteria

and Guidelines for Evacuating Storage Reservoirs and Sizing

Low-Level Outlet Works [45].

o Floods. Although not typical, some outlet works are used in passing

floods. If this is the case, flood routing steps similar to those noted for

the spillway should be employed.

• Refine discharge curves based on results from previous steps and finalize

intake structure and conveyance features sizes, along with gate/valve

types/sizes.

• Depending on type/configuration of the outlet works, initial water surface

profiles to layout conveyance features (such as chute/conduit) and

terminal structure size and type.

• Final water surface profiles to finalize size and type of outlet works

conveyance features and terminal structure.

For more detailed guidance associated with hydraulic analysis/design for an outlet

works, refer to Chapter 2, “Hydrologic Considerations,” and Chapter 5,

“Hydraulic Considerations.”

1.7.2.3 Foundation Analysis/Design

The foundation analysis/design will start when locating and selecting a type and size of outlet works and parallels the structural analysis/design efforts. The following chapters of this design standard explain the steps of foundation analysis/design, including:

• Define site-specific foundation material and strength of properties.

• Assist in identifying suitable sites based on site-specific foundation needs

for an outlet works.

• Define and analyze ground water conditions.

• Develop appropriate foundation designs which include:

o Drainage features, which in many cases are the key foundation design feature. (NOTE: Identify and evaluate drainage features/systems that will be accessible for inspection using CCTV equipment).

o Adequate support for the outlet, which could range from excavating to competent rock to driving piles, placing piers in a soil foundation, or supporting excavated tunnels with rock bolts, shotcrete, etc.

1.7.2.4 Structural Analysis/Design

Similar to the spillway, the structural analysis/design of the outlet works typically follows the hydraulic analysis/design. The following chapters of this design standard explain the steps of structural analysis/design, including:

• Identify which features are considered “critical”7 and “noncritical”8

• Identify and define loading conditions for both critical and noncritical features, which will typically fall into four categories, including:

o Construction.

o Operational (normal or static).

o Flood (hydrologic).

o Earthquake (seismic).

1.7.2.5 Mechanical/Electrical Design.

The mechanical/electrical design takes place concurrently with the structural analysis/design. The following chapters of this design standard explain the steps of mechanical/electrical design, including:

• Select, size, and design gates/valves.

• Select, size, and design bulkhead gates, if applicable.

• Select, size, and design trashracks.

1.7.2.6 Risk Analysis (Only for Significant and High Hazard Dams/Dikes)

Similar to the spillway, probabilistic (in the form of a quantitative risk analysis), rather than deterministic, considerations will be part of any analysis/design for significant and high hazard dams and/or dikes, along with appurtenant structures such as outlet works. The steps will be integrated with the previous design/analysis and include:

• Identify and define credible PFMs for the existing, modified, and/or new outlet works. Although each outlet works may have some unique credible PFMs, common PFMs have included:

o Flood-induced overtopping of dam and/or dike (if outlet works are used to help pass floods).

o Flood-induced outlet works operations which exceed the original/maximum design discharge, leading to overtopping of the chute wall and/or terminal structure walls, or sweepout of the terminal structure, and leading to erosional headcutting of the outlet works foundation or erosion of the dam and/or dam foundation, overstressing the conduits and/or tunnels, introducing pressurized seepage through cracks/joints in the conduit and/or tunnels into surrounding embankment or foundation materials.

o Operational- and/or flood-induced cavitation damage typically downstream of gates/valves in the chute and/or conduit, leading to erosion of the foundation.

ANEXOS

BIBLIOGRAFIA:

AMERICAN CONCRETE INSTITUTE – ACI

LINKOGRAFIA:

- http://www.asocem.org.pe/bivi/re/dt/OH/ obras_hidraulicas_rivera_feijoo.pdf

- http://www.asocem.org.pe/web/_actual_nac/propuesta %20%20junio2011.pdf

- http://www.deq.state.ms.us/Mdeq.nsf/pdf/ L&W_StructualComponentsDesign/$File/CHAPTER40-Structural.pdf?OpenElement

- http://www.fema.gov/media-library-data/20130726-1849- 25045-1370/11_hydrosafetydam_app_d.9.pdf

- http://www.usbr.gov/pmts/tech_services/engineering/design/ DS14-1.pdf

- http://dtic.mil/dtic/tr/fulltext/u2/a212036.pdf http://www.dtic.mil/dtic/tr/fulltext/u2/a251470.pdf

- http://www.mde.state.md.us/assets/document/damsafety/ COE/Strength%20Design%20Reinforced%20Concrete%20Hydraulic%20Structures.pdf

- http://virginiadot.org/business/resources/Materials/ MCS_Study_Guides/bu-mat-ConcreteCh3.pdf http://www.fema.gov/media-library-data/20130726-1849-25045-1370/11_hydrosafetydam_app_d.9.pdf

- http://www.concrete.org/portals/0/files/pdf/ ACI_Concrete_Terminology.pdf

- http://www.deq.state.ms.us/Mdeq.nsf/pdf/ L&W_StructualComponentsDesign/$File/CHAPTER40-Structural.pdf?OpenElement